In recent years, along with the rapid development of the glasses-free 3D display technology, grating-type glasses-free 3D technology has become an important trend due to a simple manufacture process and an excellent 3D display effect. For a conventional display device with a liquid crystal grating, there exists an optimum viewing position. When a viewer is located at the optimum viewing position, the viewer's left eye and right eye may view a corresponding left-eye image and a corresponding right-eye image respectively, and at this time, an optimum 3D display effect may be achieved due to low crosstalk. However, when the viewer is located at a position other than the optimum viewing position, i.e., when the viewer's eyes move front or back relative to a screen of the display device, it is impossible for the viewer to view the corresponding images, and at this time, the 3D display effect may be adversely affected due to the significant crosstalk.